FlightGear 2020.1.2 Released

FlightGear 2020.1.2 contains bug-fixes and improvements to the 2020.1 release. For users experimenting with the Compositor renderer, there’s now clearer information on startup, and a simple interface to select the display settings (performance or higher quality)

Bugs affecting macOS users when updating from an older version were fixed, as well as other bugs in GPX flightplan loading.

As usual, grab the updated files here

FlightGear 2020.1 released

The FlightGear development team is delighted to announce the 2020.1 release of FlightGear, the free, open-source flight simulator. This version is a preview of our next stable release, containing many new features and improvements.

Enhancements since 2019.1 include a developer preview of the upcoming Compositor graphical rendering framework as a separate pre-built binary, better aircraft carrier support, improvements to both the JSBSim and YASim flight dynamics models, better view options, more efficient and improved OpenStreetMap buildings and translation of the UI into Polish and Slovak. Here’s the complete list of changes.

Many aircraft have been updated, including major updates to the Boeing 777, Airbus A320, Antonov AN-24, F-16, Piper J3Cub, Saab JA37 Viggen, Piper PA28 Cherokee, Bombardier Q-400, Space Shuttle.

Founded in 1997, FlightGear is developed by a worldwide group of volunteers, brought together by a shared ambition to create the most realistic flight simulator possible that is free to use, modify and distribute. FlightGear is used all over the world by desktop flight simulator enthusiasts, for research in universities and for interactive exhibits in museums.

New stable release: 2018.3.5

There’s a new stable (long-term supported) release just available on SourceForge : 2018.3.5. This contains some smaller bug-fixes but most importantly, the build now works correctly on macOS 10.15 Catalina. This required updating many internal aspects of how we build the software, which took considerable effort from a whole team of people.

Get the new release while it’s hot: from SourceForge.

A preview of the 2018.3 release

A change to the release philosophy

After introducing the scripted releases four times a year, the FG development team decided to have a discussion to compare this experience with what we had before, and the result of this is that we want

* less changes of the default airport
* make one of the four yearly releases especially stable

This stable release is planned to be the fall release – so you can expect this to be especially well tested.

What else will there be?

The new C-172p

Flightgear’s default aircraft, the C-172p, is now better than ever.

The cockpit has received a lot of improvements, including new recess casings and glass reflection effect to all instruments, previously missing panel parts have now been included, such as alternate static source knob, low voltage LED, lighter hole, a working glove pocket (which holds the GPS device when not in use), sun visors, and PPT cables connected to the yokes. Other improvements include 3D model and textures changes to all levers, toggles, seats, magneto keys, EGT gauge, attitude indicator and ammeter gauge. An ambient occlusion map has been applied to all interior textures, making the cabin look much more realistic.

The plane now makes use of lightmaps, making night flights much more immersive than before. These include post lights, which are installed on individual gauges, a red flood light which can be used during night flights too, and a white dome flight and wing courtesy lights to be used while in the ground during the pre-flight checks. The lightmap illumination responds to the environment light and dims during daylight.

The exterior model has also received some improvements. It now has a much improved vertical stabilizer model, including a retopologized beacon model, and all of the aircraft antennas have been redesigned as to match the gauges in the model P.

The aircraft has also received new sounds: clicking on the checklist in the pocket by the pilot seat, toggling the control lock, mounting and dismounting the GPS from the panel, opening and closing glove pocket, moving the window latches, and toggling the water rudder cable. The flaps lever and flap motor have also received sound improvements.

Other than that, the tutorials and checklists have received much attention, including two new tutorials: take off and landing for float variants. This release also fixes many bugs, among them an adjusted P-factor effect, making the flight model more realistic.

New cloud lighting

In the Atmospheric Light Scattering renderer, an experimental new option for more detailed cloud lighting is now available. This includes diffraction and rainbow effects on high Cirrus clouds as well as more dramatic darkening and silver-lining for lower clouds seen against the sun.

For clouds seen with the sun, Mie scattering is simulated which darkens the fringes of clouds.

(Note that this is an experimental option and may not yet always work as intended.)

Display visuals

Aircraft developers can now use a new effect for displays, which simulates both the eye response to too bright or too dark display settings for the ambient light level and the visuals of dust on the screen surfaces for glancing light angles.

(Note: This needs to be implemented per aircraft and is not available for all.)

Scenery to explore

An exciting new spot to explore is the Arctic island of Jan Mayen, situated north east of Iceland. It received a makeover with corrected elevation data and coastlines, and is now available via TerraSync. The volcano, Beerenberg (2277m) is also now one of the active volcanoes simulated in FlightGear, making for an impressive sight as the snow covered peak belches out smoke and ash.

The island’s airstrip, Jan Mayensfield (ENJA), has a 1600m dirt runway, perfectly suited for the DHC-6 or c172p’s skis.”

Other improved aircraft

Besides the C-172p, several other craft also have received improvements, including

– Improved low speed handling, flaps aero rework using OpenVSP, spoiler aero added for yaw, adjusted effectivity at higher alpha based on pilot reports and OpenVSP analysis
– APC now holds alpha rather than airspeed.
– Wingsweep (oversweep) now modelled correctly, wing bending (G load, damage), JSBSim systems rather than Nasal.
– alpha indicated has been aligned based on the touchdown geometry of the hook; optimised for 15degrees indicated.
– carrier and tanker now included in replay

– Exterior model improvements and revised liveries
– added conformal fuel tanks (IAF, AF86-0023),
– MK-84 air to ground support,
– performance improvements (canvas, cockpit model merged with texture atlas), should work better on lower spec. systems.
– more accurately modelled autopilot
– FDM improvements (mass properties for stores corrected, stores drag, correct aero axes)
– FG Fuel&Payload works correctly with aircraft specific stores dialog

Space Shuttle

– Improvements to the visuals, including furry velcro strips
– Improvements to launch guidance and orbital plane targeting
– More realistic OMS burn procedures
– Expanded systems including circuit breaker simulation
– Expanded failure modeling including tank leakage

Other improvements

Lots of other, less visible things are happening behind the scenes:

– improved joystick configuration dialog
– additions to the launcher
– better support for starting aircraft in a certain state
– bugfixes
– and much more…

The Grand View

Earth from space

The view from a spacecraft – dark blue oceans, the multi-colored landmasses, the blue ribbon of the atmosphere and brilliant white cloudbands during the day, long shadows and hues of orange and pink in the dawn zones and finally the gleaming lights of the planet’s cities and the faint strands of aurora in the sky.

Few of us will ever have the chance to go to ISS and view the ‘pale blue marble’ from low Earth orbit – for real that is.


Matters are quite different in a simulation of course. Over the last years, Flightgear’s rendering engine for views from orbit called ‘Earthview’ has undergone a lot of improvements and additions, making it one of the best visualization tools available.

Lots of work has gone into the visuals at night. For example, a fairly sophisticated model of Aurora Borealis and Australis colors the sky around the poles. See a diffuse green glow of high Oxygen excitation for low solar activity, or a full auroral arc with slow red Oxygen lines high above, sharp green glow of Oxygen following the field line structure further down, culminating in the purple fringe of Nitrogen excitation.

The night lights of the cities are taken from the NASA visible Earth project – but they are post-processed by a shader to give them the appearance of being composed of millions of small lights.

As a special treat, there are even some thunderstorms with lightning momentarily illuminating the storm cell in a number of places – beware, they are not easy to find!

Earthview also comes with its own runtime-adjustible model for scattering in the atmosphere – dry scatterers give the scene a blue hue, wet scatterers make it appear foggy. The amount of scattering follows the path through the atmosphere – there’s less atmosphere effect on mountains and high plateaus than at sea level. Even a semblance of weather changes can be simulated by either moving the cloudsphere or dialing the density of clouds.

The relief mapping on the terrain give it a 3d appearance, and post-processing adds the appearance of details up to a few dozen meters in size scale. Like the terrain, the cloud map is also post-processed to show shadows and 3d appearance using parallax mapping, and clouds cast shadows onto the terrain – all of which combines to make the scene come alive.


Ready to take the trip?

Flightgear has a handful of vehicles which can reach into space, but only two which allow to insert into a stable orbit – the Space Shuttle, and the Vostok-1 carrier. While learning to operate the Shuttle takes some time, Vostok is now equipped with automatic launch guidance, making it a good choice for your first trip into space – like Gagarin, you can just sit back and ride it out.

If your memory and graphics card permits it (8+ GB are a good idea), now would be the time to install a few GB of hires textures linked on the Earthview Wiki page. These textures are not part of a normal FG installation since they are substantially larger than the whole FG data package.

At every step, you can follow the Vostok stage separation in outside view and see the discarded rocket stages disappearing behind you as the next stage ignites.

Once in orbit, you can even try to maneuver around the TDU and get back to the discarded 3rd stage.

There’s not much in terms of maneuvering the Vostok capsule can really do, so you might as well enjoy the view for a few orbits, and eventually turn it around for a de-orbit burn that brings you back onto the ground.

The simulation can’t give you the real feeling of weightlessness, but it tries to bring you close – in the Space Shuttle, you can put a flight data file folder in free-float mode into the cabin – you can watch Earth through the windows while the manual slowly floats through your visual field.

So, get out on the pad, launch into space and enjoy the grand view!

Further reading

The Earthview project page
The Earthview wiki page
The Vostok-1 wiki page
The Shuttle project page

A preview of new features in the Honolulu release

Discover Hawaii

The first FG release in 2018 will move to the tropical island of Oahu, using Honolulu as the default airport. In preparation, the islands of the Hawaii chain have received a makeover – textures for the typical shrub vegetation has been added, the terrain texturing has been improved and the airport layouts have been re-generated.

There’s now a lot of new things to discover – fly to the ‘garden island’ of Kauai and look for waterfalls, search for the new highly detailed aircraft carrier ‘Harry S. Truman’ cruising close to Oahu, watch a sunrise from the summit of mighty Haleakala on Maui or discover an active lava fountain on the ‘big island’.

Active volcanoes

Have you ever seen a volcano eruption in a flightsim? This is your chance – in the upcoming release, you won’t only be able to see lava pools and volcanic smoke of Puu’Oo on Hawaii, but also see lava fountains of the Italian volcano Stromboli and even the mighty ash plumes blown high into the air by an eruption of Etna on Sicily. The activity of all these volcanoes can be adjusted from the Environment GUI.

The current implementation is still limited, but in the future, volcanic ash might actually interfere with the weather and aircraft operations – just like in reality.

Unprecedented vegetation detail

Using geometry shaders, the Atmospheric Light Scattering rendering framework now offers the option to see dense volumetric grass layers on the airport greenspaces, as well as rendering additional 3d layers of vegetation underneath the regular random trees and shrubs in regions where this is configured. This offers the eye a pleasantly high level of detail even at close range and adds much to the visuals. While this technique might be heavy for older graphics cards, the performance on a modern high-performance graphics card is excellent.

A helpful co-pilot

Have you ever wanted to fly a helicopter, but didn’t manage to get it off the ground? The Alouette-III now comes with a helper (or flight instructor) for you – Amelia.

Amelia (named after aviation pioneer Amelia Earhart) is an animated co-pilot capable of taking off, landing and hovering the helicoper for you, according to your instructions. You can simply ask her to get the craft off the ground for you, then fly it a bit forward and then take over from her. Or, if you’re interested in operating the winch and doing rescue operations, she can hover over a spot and move slowly to the right spot according to your directions.

New and updated aircraft

A lot of development has happened for various aircraft – for instance the Robinson R44 helicopter has received a stunning new 3d model and many systems are now simulated in detail.

Another great addition, both in terms of visuals and systems, is the new Cessna C-182. If you like single prop aircraft and want to see something more modern than the default C-172p, try it out – it makes for a great plane to do sightseeing in Hawaii!

The carrier handling of the F-14b is now much more realistic, with arrestor wire effectivity dependent on speed at touchdown, more realistic low speed aerodynamics during the approach and correct ‘kneeling’ of aircraft when on the catapult – take the F-14 to the ‘Harry S. Truman’, and you won’t be disappointed!

Lots of details have also been added to the Citation-II business jet and bugfixes, gear damage, a correct autopilot and an improved radar to the F-15.

…and much more

Much more work going on behind the scenes:

* improved usability and integration of the Flightgear launcher
* fixes for AMD graphics cards rendering issues
* many other small bugfixes
* improvements to the YaSim flight dynamics engine for better realism

Stay tuned as we launch the next release!


FlightGear FGMEMBERS Statement (v2.2):


What you see today as FlightGear is the result of 20 years of collaborative development effort by hundreds of talented people all working together to provide a freely available GPL flight simulator that anyone can contribute to.  The core FlightGear team feel that it is important to make a clear statement of their position concerning the FGMEMBERS organization, explaining why it is important to continue working in a way that will ensure that FlightGear continues to prosper for the next 20 years as well as to clear up any confusion and FUD that has been disseminated by members of the FGMEMBERS organization.

The FGMEMBERS infrastructure offers little benefit to contributors.  From experience, the core team knows that the lack of appropriate controls on contributions may, after a long period of time, lead to a divergence that may result in contributions being lost.  This includes the divergence of models as well as scenery enhancements that are not contributed to the scene models database.



During five years of in-depth discussions on the development mailing list (where decisions are made[1]) a consensus of opinion was reached which defined the future direction for the core assets of the FlightGear project.  This required the removal of the aircraft models from the old fgdata repository[2], leaving the core assets and the default aircraft.  Unfortunately this necessary change resulted in a fundamental disagreement with a couple of FlightGear users who demanded that the decision making process be restarted[3].  Clearly with five years of discussions already undertaken it was not a viable path forwards to restart discussing the splitting of the assets and which revision control systems were most suited for the FlightGear project.

One of the objectives of the project is longevity and ensuring that the path taken is, with the best available knowledge, as future proof as possible, allowing authors to make their contributions with the minimum amount of disruption whilst maintaining quality and licencing standards.

As a result of the disagreement, one contributor started what is generally considered to be a hostile fork of the core asset repositories into what is known as FGMEMBERS.  This was expanded to include all the other models and assets from all non-official repositories from all corners of the internet, to form a single source for all contributed assets (core assets, aircraft, scenery, 3rd party hangars, etc.).  At a first glance this appears to be a good idea, as there is a single place where everything can be found.  However the disparate nature of contributions means that FGMEMBERS is a divergence of most of the original content.  Whilst certain repositories may be up to date within FGMEMBERS, it is not necessarily true that this will remain the case.  Taken together, this negates the key benefit of a single location for all content.  The other key point is that any changes contributed to the FGMEMBERS infrastructure may never make it into the original repositories.  This affects the availability and quality of models for the wider community of the FlightGear project, such as the aircraft that are available for download on the FlightGear website and launcher[4].  Any contributor spending considerable time making changes to aircraft or scenery may be unaware that their changes may be lost in the future, especially in the case of scenery as the FGMEMBERS scenery workflow is to modify what is considered to be an automatically generated set of temporary files from base data sources.

Since its inception, the FGMEMBERS organization has continually made very emotive statements and accusations regarding the core development team and the way the FlightGear project is run.  The core FlightGear team consider those baseless and has refuted them.

Official FlightGear Position

The core FlightGear team considers the FGMEMBERS data asset forks to be hostile and the infrastructure bad for the FlightGear project for a number of reasons:

  1. Historically, forks of Open Source projects are unsustainable because developers choose one or the other.  Over time, the vast majority of forks die.  In a small minority of cases they become prevalent and the original dies.  In either case, a huge amount of effort is wasted on the fork that eventually loses.  We feel that effort is better spent on improving the simulator.
  2. It is inevitable that the fork will diverge, as changes are made to one repository but not the other.  Attempting to keep the repositories in sync requires huge amounts of effort and is likely to fail due to incompatible changes being made to the same file by multiple developers.
  3. The FGAddon repository is actively supported by the core development team, with processes in place to ensure the long term health of the repository, and compatibility with any changes to the FlightGear core.  The core FlightGear team have been working on this project for 20 years and has a long track record of ensure the long-term health of the aircraft.
  4. We are concerned that FGMEMBERS deliberately does not have controls over commit access to the repository and as a result license violations have occurred.
  5. Different versions of the same aircraft existing in both FGAddon and FGMEMBERS causes confusion and adds to the burden of support from volunteers who may not have the same version.  This makes tracking down bugs much more difficult.
  6. We object most strongly to the way that FGMEMBERS proponents have evangelized against FGAddon and TerraSync and the accusations that they have made against the core team.  We consider this unacceptable.
  7. The constant and active recruitment of potential developers away from the core infrastructure has caused and is causing a lot of long term harm to the FlightGear project.

The FlightGear development team encourages users and developers to use the official repositories and infrastructure (FGData, FGAddon, TerraSync) and continues to support 3rd party hangars.


Why is this important?

Question: What is the point of this document?

It is important that we all work together to ensure the continued growth and development of FlightGear.  The core team does not want to see valuable contributions being lost because these contributions were made to something outside of the FlightGear project.  What you see today exists due to the time and effort of developers.  Unfortunately in recent years FGMEMBERS has proved to be a considerable waste of developer time that could have better been spent on improving things rather than dealing with and refuting allegations, answering questions from confused users and declining attempts to reopen discussions that have no relevance for the already decided future path of the project.

Why is FGMEMBERS considered as a legal liability?

Question: Why is the core design of the FGMEMBERS system considered as a legal liability?

The official FlightGear infrastructure operates on a basis of trust and experience, in which a committer must be prepared to accept the trust of everyone else and show an understanding of copyright issues.  This is in stark contrast with the FGMEMBERS principle that everyone and anyone can obtain commit access for improving the system.  The FlightGear way has been proven to work over many years as it results in collaborators who can be trusted not to cause damage to the FlightGear project or to cause legal jeopardy by a lack of understanding.  Without this there is an elevated risk that an inexperienced content developer may deliberately or inadvertently obtain material (3D artwork, photographs, sound bites, etc.) found somewhere on the web and include it within their own GPLv2+ licensed content without due consideration of the licencing implications.  The official FlightGear infrastructure has the *-commitlogs mailing lists[5], allowing individual commits to be reviewed; whereas FGMEMBERS has no such system and as such can be considered as a more anarchic system where illegal content will inevitably be added under the radar.  This is unacceptable in a large open source project such as FlightGear as it puts the contributor and the project at legal risk.

Why use the “hostile fork” terminology?

Question: Why is the FGMEMBERS infrastructure referred to as a “hostile fork”?

This is standard software development terminology for the FGMEMBERS situation.  Here is one definition:

  • “A HostileFork happens when someone isn’t happy about the way a collaborative effort is being run, so they start their own competing project.  They take the work of the group in a different direction…rather than working on achieving a consensus.  Often they lobby for developers to assist their effort, rather than the original project from which they are derived.”[6]

And another:

  • “A hostile fork is one done unilaterally, generally without consultation or the blessing of the main project.  It generally causes acrimony and community fragmentation, and usually no code changes are shared between the forks after the split.Compare to forking to solve a very specific or specialized problem that doesn’t make sense to merge upstream, like a set of changes that only apply to a very narrow audience or esoteric use-case.  In such a case, it’s common that changes that do affect the main project are still merged upstream and special care is done to make sure the forks don’t diverge too much.”[7]

The core group consider the current situation to be an exact match to the “hostile fork” definition.

Why not consider the FGMEMBERS proposal?

Question: Why is the design and operation of the FGMEMBERS system considered as unsuitable for use as the official FlightGear infrastructure?

Firstly, the proposal was made years after a consensus had been made and a decision reached.[8].

Secondly, the design is considered to be incompatible with how the FlightGear community operates.  The FlightGear community is bound together by mutual respect and basic courtesy; there may be disagreements but it is expected that disagreements be handled in a respectful way without personal attacks.  The wishes of all contributors wherever possible are respected.  There are some models in FGMEMBERS in which the original authors have directly stated a wish to not have their aircraft be distributed as part of this system.  Instead of respecting that wish, these aircraft remain bundled as part of the FGMEMBERS.

Another concern, and in many ways for the community a large concern, is the encouragement to make contributions outside of the official or original author’s distribution channels.  This is a key aspect of the FGMEMBERS system used to advertise to new users that the FGMEMBERS system is superior to the original upstream sources.  Hence the FGMEMBERS system strongly competes against those wishing to be independent of the system, using an “improved” version of their own work.  To avoid this, a number of content creators have used specific licensing to legally block FGMEMBERS redistribution.  But in the process these authors have lost part of their freedom that the GPL licence offers — the same freedom that has allowed FlightGear to become what it is today.  This is causing long-term damage to the FlightGear project and the GPL ecosystem built around it.

We consider that redistribution for solely aggregation and deliberate divergence of GPL-licensed content is permissible legally but morally questionable.  Particularly when it is against the wishes of the original author, and implicitly competing against that author for the aim of selling the FGMEMBERS system.  This is considered unacceptable as a model of operation for the FlightGear project.

Why not peacefully coexist?

Question: Why is FGMEMBERS different from all of the other 3rd party infrastructure and peaceful coexistance not possible?

The aim of the FGMEMBERS organization is to attract as many FlightGear users and content developers as possible to become the de-facto FlightGear content infrastructure.  To achieve this, FGMEMBERS deliberately aims to minimise or completely cut off contributions upstream to the core FlightGear infrastructure for the sole purpose of rendering it irrelevant.  However as the same design is used for both the core infrastructure and the 3rd party infrastructure, this affects the whole of the FlightGear community equally.  FGMEMBERS hoards absolute all of the content from all content creators, but then applies fixes and improvements that are not submitted back upstream to the original authors, using the excuse that upstream should find and backport the fixes themselves.  This is specifically to use as a selling point against the official and 3rd party FlightGear content infrastructure.  Because of this positioning, the FGMEMBERS organization is unlike any other 3rd party infrastructure — it is not complementary to the FlightGear ecosystem but is rather competitive to it.

Why is syncing not possible?

Question: FGMEMBERS intends to sync all changes from FGAddon, why can’t FGAddon simply merge all the changes from FGMEMBERS so the repositories remain identical?

There are three reasons for this.  Firstly, over time the repositories will diverge in a way that is impossible to reconcile (e.g. two different developers with different end goals modify the same aircraft model at the same time).  Secondly, such a merge would require a large, continuous amount of effort just to maintain a position that would exist without FGMEMBERS.  Thirdly, we have concerns over the attitude of FGMEMBERS to licensing and accepting almost all content, and are not prepared to legally risk the GPL “health” of FGAddon.

For many years it has always been that FGAddon and its predecessor infrastructure is the definitive place for the FlightGear models.  As part the FlightGear contribution workflow, the responsibility is on the content author to contribute to FGAddon when their work is ready for release.  Once the work is present in FGAddon, the author is then expected to maintain the aircraft in FGAddon.  This is how development has always been performed and it works well and everyone understands it.
To change this now so that it becomes the responsibility of someone else, other than the contributor making the changes is clearly an unworkable solution.  However the published procedure for adding or modifying FGAddon does not preclude contributions from anyone who is prepared to follow the submission rules and content guidelines.  So FGMEMBERS could, if they so wished, follow these procedures to ensure that FGAddon remains the core asset that is definitive and up-to-date.

Why not switch the core infrastructure to FGMEMBERS?

Question: Why can you not work with the FGMEMBERS team to create a single repository?

Primarily this is not possible as it would require reopening a discussion that was ongoing for 5 years — and this approach is merely a different way of doing things that does not provide any real benefits to the long term goals of the project.

Why Subversion?

Question: Why do you use Subversion instead of my preferred version control system?

Subversion was agreed upon during the discussions on the development mailing list as it provided most of the required facilities in a way that worked for the wider community.

Why have gatekeepers?

Question: Why does FGAddon have gatekeepers?

The official policy[9] is designed to allow for easy access to FGAddon for contributors whilst maintaining quality and legal standards.  As the official FlightGear repository has obligations and legal liabilities, the gatekeepers are there to ensure these quality guidelines are met.  The gatekeepers are friendly and helpful — their role is to promote the development of aircraft while respecting the community rules and to guide new contributors; who themselves may gain, or already have, the experience to be a gatekeeper.

How do I contribute?

Question: How can I send improvements to FGAddon for inclusion into the official repository of aircraft?

As detailed on the FGAddon wiki article, there are a number of steps.  Firstly the original aircraft authors should be contacted.  If this is not possible, then send an email stating your intentions to the FlightGear development mailing list or post a message on the forum.

Why should I contribute upstream?

Question: Why would I want to contribute to FGAddon when I could just hack away and publish my changes in a forked repository?

Contribution to FGAddon guarantees the widest distribution of your work by including your work into the FlightGear project (your improvements will be available on the official download page and inside the launcher).  You are also contributing back and collaborating with the FlightGear project.  This is a proven method to ensure continued and long term availability of your improvements for years to come.  If an original aircraft developer is still active it is normally considered respectful to work with that author as it will often benefit everyone involved, rather than taking their work and competing against them.  Otherwise this will result in two versions that have different improvements, when the goal should be to all work together to provide the best models that collaboration can build.

Can I obtain commit access?

Question: Is it possible for me to obtain commit access to the FGAddon repository?

You are encouraged to apply for commit privileges as soon as you feel that you meet the criteria and are ready to take on the responsibility[10].  If in doubt, send an email to the FlightGear development mailing list.

Is FGMEMBERS a 3rd party hangar?

Question: Are the FGMEMBERS aircraft repositories considered as a 3rd party hangar?

Answer: No.
As FGMEMBERS has aggregated all of the FlightGear assets, including FGData, FGAddon, TerraScenery, 3rd party hangars, and all other sources, the aircraft component of this system is not considered as a 3rd party hangar.  As it is a hostile fork, unlike the 3rd party hangars, it competes directly against the official FlightGear data assets and infrastructure as well as the 3rd party hangars.  It also competes for developer resources against the FlightGear project and 3rd party hangars.


We believe that the best path forwards for FlightGear is for the community to work together.  We recognise the importance of contributors and collaboration and positively encourage everyone to work together with the common goal of improving FlightGear in a positive way, and to be respectful, honest, trustworthy and fair.  Let’s get the word out and make sure that FGMEMBERS has to communicate with a well informed audience.


Helicopters in Flightgear

The Art of Hover Flight

While most Flightgear users seem to mainly use GA aircraft or airliners, the simulation of helicopters is not only possible but comes with a nice degree of realism. This makes learning to fly a helciopter quite a challenge, but also very educational.

Why not try it out?

Piloting a helicopter is also a nice opportunity to see the terrain in a different way, because usually the view downward is much less restricted than in aircraft cockpits – here a good graphics card to support all the hires terrain texturing and the various vegetation and building overlays that can be enabled really pays off. And of course you can land pretty much anywhere you like, airports are no longer a must, any flat patch of terrain will do. But there are also hundreds of helipads in the FG scenery, located on places like hospital rooftops or oil rigs.

Ready for takeoff? Let’s take a quick look at some helicopters FG has to offer.

Helicopter flight

If you’ve mastered flying normal aircraft and have the idea that helicopters can’t be so different, you’re likely wrong – helicopters are very different.

Normal aircraft are usually dynamically stable – if they feel a perturbation, they return to a stable attitude. Helicopters reach this condition only when they accelerate, but just after takeoff and before landing they move through the air slowly, and they’re in fact dynamically unstable – any perturbation needs to be countered quickly with the controls, or it will grow and the pilot will lose control.

Another thing that takes some time getting used to is that the body of a helicopter swings like a pendulum underneath the rotor. The pilot always needs to recognize when a motion is part of this oscillation and will dampen out on its own and when it is actually part of the flight dynamics.

Yet perhaps the hardest thing to master for beginners is the torque of the rotor. The rotating blades try to yank the helicopter around against their own motion, and only the action of the tail rotor prevents this – so pedals need to be used carefully to counter this effect.

So how is a helicopter controlled?

Unlike in an aircraft, the turbine RPM is usually not throttled. Rather, the angle of the main rotor blades is changed by the collective control- this provides upward/downward motion. The main rotor can be tilted by moving the stick, this provides a combination of forward and sideward motion. It is actually quite feasible to fly a helicopter sideward, or even backward if it is done slowly, only once the airstream becomes fast, the fuselage tries to align with the wind like for an aircraft. Finally, the pedals control the tail rotor action – they can be used both to stabilize the craft against the main rotor torque as well as swing the nose around into a new direction in hover flight.

The final important ingredient to understanding helicopter flight is the ground effect. If the air displaced by the main rotor can’t go anywhere quickly because there is terrain underneath, it forms a ‘cushion’ of air that keeps the helicopter afloat. The effectivity of this cushion decreases quickly with altitude, thus close to the ground the collective actually controls altitude rather than vertical speed. Setting the rotor to displace more air pushes the helicopter upward, but then the ground effect decreases, so the craft settles at a new altitude.

A helicopter is then taken off by hovering into the ground effect, then using the stick to induce a forward motion (which gradually causes more lift on the rotor blades), and only when it is faster than some minimum speed flown out of the ground effect region. Similarly, one can expect and anticipate the ground effect for a landing.

While all these effects are there for any helicopter, the degree to which they make themselves felt differ quite a lot, and so every craft has to be learned separately.

The Robinson R22

If you were to attend real helicopter flight training, the Robinson R22 is the type of helicopter you would most likely encounter – it’s a low cost craft, popular throughout the world as a trainer or utility helicopter. The R22 has a low inertia rotor system, and the control inputs are transmitted directly by rods without hydraulic assistance. This means that the controls have to be moved very gently to avoid overcorrecting, and overall the helicopter reacts rather finnicky. This does seem to make it a bad choice for a trainer, except the idea seems to be that if a flight student masters the R22, she won’t have any problems with a heavier helicopter.

The instrumentation is generally simple, giving the pilot an almost unhindered view through the windshield.

In Flightgear, the R22 definitely exhibits the characteristics of the original counterpart. There’s lots of torque which is difficult to compensate, and you need to work a lot for even a halfway decent hover flight. Also, bringing the R22 into level flight with a good trim is far from trivial.

The Alouette III

The Alouette III is an aging light utility helicopter, in service since 1960, mainly used by military forces around the world, used for tasks ranging from passenger transport to aerial ambulance and SAR. Compared with the R22, it is a much heavier machine and hence considerably less skittish on the controls.

In the Flightgear version, the startup and shutdown sequences are implemented and the instrument panel is largely functional. What takes a bit to get used to is that this helicopter has wheels rather than skids, which makes sometimes for a surprise when landing in sloped terrain.

The Sikorsky S-76C

As a medium-sized utility helicopter, the Sikorsky S-76 dating to the 1980s comes with quite a bit of modern avionics aboard. Two turbines pack a lot of power, and the craft also features a retractable gear for better cruise performance.

Unfortunately, the avionics of this helicopter is not fully implemented in FG, but it nevertheless is a nice classy craft to fly.

The Chinook CH-47

The mighty Chinook CH-47 is a heavy lifter used by the US Army since the 1960s, both for transport as well as for aerial assault purposes, inserting troops behind enemy lines.

Unlike any of the helicopters above, the craft features counter-rotating twin rotors which removes the need for a tail rotor. This (and the large mass) make the flight fairly stable and the helicopter feels a bit sluggish at the controls.

Unfortunately, many instruments are modeled in the panel but not actually working, which limits the experience somewhat.

The Eurocopter EC 130

A truly modern light utility helicopter, the Eurocopter EC 130 was introduced in 2001 and is in strong demand around the world. It comes with a modern avionics set and (for its weight) a fairly powerful engine.

In the simulation, the EC 130 is, hands down, one of the most stunning models with a photorealistic exterior utilizing pretty much every rendering effect available. Once in the cockpit, there is a detailed startup and shutdown procedure available that’s supported by the checklist system. In addition, many different configurations and pieces of equipment (such as external baskets or a serchlight) can be chosen. Once you try it, you’ll love it.

The Eurocopter EC 135

Introduced in 1996, the EC-135 is another modern light utility helicopter used for multiple purposes ranging from medical transport and SAR to sightseeing. Powered by two turbines, it packs even more horsepowers than the EC-130.

Both the interior and the exterior of this helicopter show in FG at photorealistic quality. The EC-135 is a truly remarkable piece of work, both in the flight characteristics and visually.


Eager to try out helicopter flight now? While the R22 is what real flight students learn with, the craft is very hard to master without the helping hand of an instructor. Since you’re not paying for simulated damage or flight hours, you might as well start with a heavy machine such as the Chinook to get a feeling for the basics of helicopter flight without the complication of rotor torque, and then move on to a ‘nice’ machine like the Alouette III before tackling the really hard craft.

Don’t be discouraged by failures – you’ll probably crash the first dozen times before getting the ride off the ground properly, and it really takes a while to get the correct ‘feel’ for the controls such that good hover flight and precision landings are feasible. This is much harder than flying an airplane.

For a good introduction to the techniques of helicopter flight in FG, see the Flightgear Wiki.

Discover Alaska

Outback flying with the Twin Otter

If you’re looking for a challenge away from busy airports, IFR flight and traffic controllers try flying up in the North for a while. Remote dirt airstrips, spectacular scenery, challenging mountain flights, tricky navigation in rough weather – Alaska offers all of this and more.

In such a sparsely populated region, you need a special kind of plane – easy to maintain, with a short takeoff or landing distance and capable of taking a lot of punishment. Such as the Twin Otter.

Meet the plane

The de Havilland Canada DHC-6 Twin Otter is STOL-capable small passenger turboprop aircraft, ready to carry up to 19 people. The sturdy, non-retractable undercarriage, the short takeoff and the high rate of climb make the aircraft very suitable to serve small airstrips in remote and mountainous areas. In addition, Twin Otters can be fitted with wheels, floats or skies, allowing them to operate even off reinforced runways.

With a cruise speed of 150 kt, a service ceiling of 25.000 ft and a range of about 800 miles, the aircraft does not have the abilities of commercial jets, but its handling qualities more than make up for it.

The Flightgear version of the Twin Otter has a lot to offer – starting from a spectacular 3d cockpit over lots of simulated systems to detailed procedures. When starting in the plane, you find it in secured position, with external power connected.

Every flight starts with the pre-flight inspection, the tiedowns and pitot tube covers have to be removed, the wheels unblocked. Using Flightgear’s walker feature, you can literally get out of the plane and walk around, doing your pre-flight checklist.

Once you climb into the cockpit, you can then start the engines and switch to internal power. The plane makes excellent use of the checklist feature, with the ability to highlight every control that needs to be operated next, so you won’t get lost easily.

The cockpit artwork is simply great, close to photo-realistic, and there are lots of details to discover, from the way the windshield heater has a real function to ‘No Smoking’ signs for the passengers.

The flight dynamics is modeled using YaSim, which doesn’t make it overly realistic at the corners of the operational envelope, but the basics are all there and the simulation nicely captures the STOL and high climb rate of the plane. There’s no simulation of damage due to overstressing the plane done, but callouts of limit violations can be activated (and of course you can crash and destroy the plane).

If you’re in for a real challenge, start with a variant that has either floats or skies – if you have floats, you can actually select starting sites on the water (or get the option to re-position to a nearby site).

Mount Logan

A very nice bit of scenery is East of Valdez (PAVD) following the Bagley Ice Field towards the Seward Glacier at the foot of Mt. Logan, which towers a full 19,501 ft above sea level.

The Twin Otter will be able to take off from almost any small airfield, so we can explore this from Cape Yakataga (PACY). It’s going to be a cold flight, so remember to activate Pitot tube and propeller heaters, otherwise there’ll be nasty surprises later.

Fly north and start climbing over the first mountain ranges at about 10.000 ft – behind the peaks you’ll get your first visual of the Bagley ice field stretching in east-west direction.

Follow the glacier east until you see towering Mount Logan to your left, reaching up to almost 20.000 ft and opposite to it, slightly lower, Mount St. Elias. Then turn towards Mount Logan.

If you have skies equipped and dare to, you can try landing on the Bagley field or on one of Logan’s glaciers – it’s quite a challenge.

The Twin Otter reaches high enough to make the summit of Mount Logan, so start climbing again. If the visibility is good, you can see several other towering peaks over in Canada.

Turn back west and follow the glacier valleys branching north of Bagley field, forming the Logan glacier.

You’ll be rewarded by stunning views deep into ice-carved valleys.

Follow the Logan glacier valley till the ice disappears and mighty watercourses carry the meltwaters of the ice fields. We’re going to end the flight at Jakes Bar, which is a small dirt airstrip in the middle of nowhere. Like many small field in Alaska, it doesn’t come with a radio beacon, so you’ll have to find it by eye – it’s where a meltwater stream coming from the south merges with the water from Logan glacier.

There’s not much space here – but nothing the Twin Otter couldn’t handle.

Juneau and surroundings

Quite different but equally stunning scenery is found in the vicinity of Juneau airport (PAJN). Here the sea meets steep mountains and glaciers and fjords and islands dominate the scene. Equip your Twin Otter with floats to enjoy this best – you can start right in the water, for instance at Tenakee.

Admittedly starting the engines in the water is a bit ticky (expect to spin around while only one engine is running…), but water takeoffs and landings are really great fun (if the winds are not too strong – high surf can definitely ruin your day).

Once in the air, you can expect the flight dynamics to be somewhat different (the floats after all have different drag), but the Twin Otter has very high engine power, so it’s never a problem.

You can fly across forst-covered hills, majestic straits and explore remote bays, or fly over the Taku glacier north of Juneau – there’s plenty to see.

And the best part is – with floats you can land pretty much anywhere you like!

Again, maneuvering on the water can be a bit tricky, differential throttle on both engines, or even putting one engine into reverse thrust works best. And if you want to land on solid ground again, there’s still an operational gear attached to the floats – just don’t forget to extend it!

Save flying!

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